From a bacteriological perspective, the tongue is the largest, yet most neglected soft tissue structure in the mouth. To date, we have little knowledge of the composition of the tongue flora in health and disease. Its role in the pathogenesis of oral infections is poorly studied, but scattered reports indicate that the tongue may play an important role in prevalent oral afflictions such as halitosis, and possibly periodontitis. Periodontal organisms have been recovered from the tongue but we do not know whether their presence is a chance event (i.e. transient) or if these organisms are part of the established micro- environment, thereby serving as a reservoir from which periodontal pockets can become (re)infected. Similarly, the tongue has been implicated as a major site of odor production in patients with chronic complaints of halitosis. Our preliminary research indicates that the anaerobic fraction of the tongue microflora is responsible for much of the oral odor production, yet it remains to be determined which species specifically should be targeted, and what the factors are which allow these organisms to colonize and predominate on the tongues of these patients. We hypothesize that the tongue provides a unique micro- environment which supports the development of a primarily proteolytic anaerobic microflora. Halitosis would result from a dominance of odor- producing microorganisms within this flora. We further propose a commonality of bacterial species on the tongue and in the periodontal pocket, suggestive of a reservoir of periodontal organisms outside the subgingival environment. The specific objectives of this proposal are: 1. To evaluate which bacteriological growth medium allows maximal recovery of bacterial types in samples collected from the tongue. 2. To develop DNA probes against the representative colony types, and to use these DNA probes and cultural methods as necessary to describe the predominant cultivable microflora on the dorsal surface of the tongue. 3. To determine whether halitosis is associated with an overgrowth of specific bacterial species on the tongue. 4. To determine whether certain periodontal organisms recovered from the tongue are similar or identical to those found in periodontal pockets.